The tool is Google Story Builder and here's the link.
Be sure to check out their samples on the start page of Google Story Builder.
Students create characters, develop their lines that show the interaction, explanation, or plot, add music, and save as a video.
Here's a tutorial:
Here's a Prezi with more information:
Try it with Math story problems, as a book trailer, as a review of science concepts, or a discussion between historical figures:
Earth: Center of the Universe?
Math Problems From Refranz Davis
Here is a great quick step set to Google Story Builder by Jason Carooll from Text Help
For the Pinterest Lovers, I did a search for Google Story builder and quite a few pins of samples have been posted: